Question

After Muhammad's death, which group accepted his son-in-law, Ali, as his rightful successor?

Answer 1

The group that supported his son-in-law Ali was D. the Shi'ites 

Opposite to them, the Sunni Muslims believed that Abu Bakr should be the righteous leader.

Answer 2

The question of Muhammad's successor was one of the reasons for the appearance of two factions of Ilsam Sunni and Shi'ites. While Sunni believed that Muhammad's successor could be anyone who was sufficiently competent for the religious leader, specifically in this case Abu Bakr, Shi'ites believed that it must be his cousin, since Muhammad had no son, the choice was son-in-law, Ali.

The answer is: d.